1. Field of the Invention
The present invention relates to a front fork apparatus in a two-wheeled vehicle or the like.
2. Description of the Related Art
In a front fork apparatus in a two-wheeled vehicle or the like, there is a single disc type structure in which a disc plate is attached only to a front fork on one side of the right or left side of a front wheel. In the front fork apparatus mentioned above, a rider feels a yaw feeling that the front fork is shifted to one side of the right or the left during braking. Under these conditions, the handlebars for steering may be shifted to one side.
In Japanese Patent Application Laid-open No. 2004-224137 (patent document 1), there is disclosed an inverted type front fork apparatus in a two-wheeled motor vehicle or the like in which a suspension spring is provided only in a front fork in one side, for example, the left side of right and left front forks. A thickness of an inner tube of the front fork in the other side, for example the right side provided with no suspension spring is larger than a thickness of an inner tube of the front fork in the one side, for example the left side provided with the suspension spring.
In the front fork apparatus mentioned above, in the case that the front fork apparatus is compressed during braking, the front fork apparatus generates a rotation moment around a ground point of the front wheel toward the right front fork provided with no suspension spring, on the basis of a reaction force of the suspension spring.
On the other hand, when braking, the right and left front forks, particularly, a lower end portion of a tire wheel side tube is deflected to a rear side in a forward moving direction on the basis of a friction force between the front wheel and a road surface. Since a deflecting amount of the right front fork in which the thickness of the inner tube is made large is smaller than that of the left front fork having the small thickness, the front fork apparatus generates a rotation moment toward the side of the left front fork having the small thickness (the side provided with the suspension spring) around the ground point of the front wheel.
As a result, the yaw feeling of the front wheel at a time of braking is reduced by canceling two moments generated at a time of braking. A moment in a rightward direction is generated with no suspension spring depending on the presence or absence of the suspension spring, and a moment in a leftward direction depending on having the small thickness based on a difference of the thickness.
However, in the single disc type front fork apparatus in which the brake apparatus is provided on only one side of the front wheel, the yaw feeling is generated even in the front fork apparatus in which the suspension spring is provided in the front forks on both the right and left sides, or in which the suspension spring is provided only in the front fork on one side.